(62b) Advancement Measurement Techniques for Validation of Computational Fluid Dynamics (CFD)

Multiphase flows and reactors are complex due to complex interactions of phases, thus design and scale-up of these reactors were least understood and mostly based on the empirical approach. Computational fluid dynamics (CFD) is theoretically sound and promising approach for the scale-up, design and process development of these reactors. However the development (in particular closures) and validation of CFD suffers from the lack of detailed experimental data which disseminates information about the local (spatial) mean as well as fluctuations data. Such a data needs sophisticated measurement techniques. In our laboratory, advanced measurement techniques like radioactive particle tracking (RPT), computed tomography (CT), gamma ray densitometry, optical fiber probes, heat transfer probes, four point optical fiber probe, two point optical fiber probe, liquid and gas tracer were developed/customized to obtain comprehensive and detailed data on different multiphase systems (gas-liquid, gas-liquid-solid and gas-solids) for advancing the knowledge and validation of CFD. Full flow field information of solid/liquid phases which includes Lagrangian flow field, local mean velocity, fluctuations velocity (in terms of RMS), turbulent quantities (stresses and kinetic energy) were obtained using Radioactive particle tracking (RPT). Computed tomography (CT) were used to obtain cross sectional phase distribution. Optical fiber probes were used to obtain bubble properties (bubble frequency, size, chordal length and interfacial area) and local heat transfer coefficient and mass transfer coefficient were measured from heat and mass transfer probes respectively. Global mixing and local mixing (diffusivity) were studied using tracer and RPT studies, respectively. Such a comprehensive data on these systems advances the hydrodynamics and heat transfer and their relationship. In this presentation, overview of these techniques and selected results using these techniques on the various multiphase systems like pebble bed reactor, fluidized bed, spouted bed, bubble column, trickle bed, upflow moving bed will be presented to disseminate the flow field, phase distribution, heat transfer, mass transfer and mixing, to demonstrate the detailed information available for the validation and development of CFD.